(1) Field of the Invention
The present invention relates to telephone switching systems and more particularly to a microprocessor circuit for control of such systems.
(2) Description of the Prior Art
Microprocessor control circuits have become well known since the development of microprocessors. Most of these circuits are used in a simplex arrangement to perform control and data transfer functions in a more efficient and flexible manner than the logic circuits they replace.
Telephone systems however require a high degree of reliability which typically results in the use of duplex microprocessors (first and second parties) monitored by a third party circuit which detects a faulty microprocessor and configures it off line. However, such an arrangement requires not only the use of a complex third party circuit but also requires diagnostic software to routine each microprocessor and the third party circuit.
Accordingly, it is the object of the present invention to provide a highly reliable microprocessor control circuit for use in a telephone switching system without the need for a third party circuit and extensive diagnostic software.